Unexpected realtime delay on task 0 on a HP8300

Do you have irq coalescing disabled?
(this is needed for Intel MACs)

auto enp2s0
iface enp2s0 inet static
address 192.168.10.1/24
hardware−irq−coalesce−rx−usecs 0

Have you tried this:

forum.linuxcnc.org/38-general-linuxcnc-q...irq-affinity?start=0

Basically using isolcpus to isolate a core for LinuxCNC and then pinning the Ethernet IRQ to that core

@PCW
I can try it - but it would seem to me that if it was an IRQ that it would happen more often than every day or two?

If there was a way to tag the time it happens, I can look through the logs for some regular task happening..

In my experience, it makes a large difference in network latency
to use isolcpus and pin the Ethernet device IRQ to the same CPU that's
running LinuxCNC's realtime.

For example, I'm typing this on a HP 800 G1 Elite that I use for normal
browsing, compilations, videos etc. At the same time, it is always running
LinuxCNC. Without IRQ pinning, it would drop (timeout)  a packet maybe
once or twice a week. With IRQ pinning, it never drops packets...

OK - that seems to have fixed it - it has been up for some days now with out the hiccup..

What I did :
installed irqbalance

I had to change this line in /etc/irqbalance.d/lcnc_irqpolicy.sh


#NIC=`awk 'BEGIN{nic=""} {if ($1=="iface") {tmpnic = $2} if ($1=="address") {if ($2 == 10.10.10.1) {nic = tmpnic}}} END{print(nic)}' /etc/network/interfaces`
NIC=enp2s0



NIC just needs the name of the interface.